Alterations in cerebral blood flow and its regulation are thought to play an important role in the pathophysiology underlying mTBI. More broadly, vascular responsiveness is an established biomarker of vascular dysfunction, with the sensitivity to detect the first signs of dysfunction. Given this, targeting measures of cerebrovascular responsiveness to quantify and track mTBI severity and recovery are key.
To date, studies have used different imaging modalities (Doppler, MRI, fNIRS) and stimulus-response approaches (vasoactive stimuli [e.g. inspired carbon dioxide], postural challenges [e.g. repeated stand-squats], cognitive based tasks, exercise) to assess the impact of mTBI on measures of cerebrovascular responsiveness (e.g. Cerebrovascular CO2 reactivity (CVR), cerebral autoregulation (CA), neurovascular coupling (NVC)). A number show promise as potential biomarkers, but which is the most sensitive is unclear as studies to date typically only use one modality and/or target only one regulatory process. Furthermore, a longitudinal, prognostic study has not been done to predict how any of these potential biomarkers relate to clinical outcomes. We will assess the utility of these functional responsiveness measures on the cerebral physiology across the range of imaging modalities and functional tests.
In addition, mTBI-induced alterations in vascular, metabolic and neural processes will impact on the balance between excitatory and inhibitory transmission within the brain. This can be measured on a physiological level using transcranial magnetic stimulation (TMS) to measure the excitatory state of the motor cortex. Indeed, these measures have been shown to be sensitive to changes in acute mTBI and in Post-Concussion Syndrome, although how well they relate to and predict clinical outcome in mTBI is not known.
For more information, please visit the Centre for Human Brain Health and the Sport, Exercise and Rehabilitation Sciences webpages.
Lead Researchers